After things settled out I have now noticed a slow pressure leak -- tank pressure drops down over an hour or so triggering pump. I shut off house side and confirmed it is back leaking into the well head, not into the house. I assume this means the tank check valve (a Flowmatic, estimated age 16+ years) is not seating fully. Tank membrane tests good, it's a well-x-trol; I don't know the number off hand , but I measure about 6.5 gals to empty it from 55PSI to empty. Backflow problem did not exist before the well pump was replaced.

Questions:

1) On restart of we brought up noticeable sand and sediment. Water is pumping and running crystal clear now, but I still get a little bit of sand if I drain the tank to completely empty. Could it be bits of sand keeping the valve from seating?

2) Should I just replace the valve anyway, for good measure rather than trying to trouble shoot it?

3) Should I worry that the check valve at the pump is not seating as well and call the installer?

It is not advisable to have a checkvalve topside and fixing it to solve a leak in the well is not the route to take.

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My bad for making assumptions. Perhaps what you have is a snifter valve meant to put air into the tank? Is it a hydro-pneumatic tank? If so, in combination with the snifter/checkvalve would be a bleeder in the well. A checkvalve by the snifter is required and if it leaks, will cause water to bleed back constantly.

LLigetfa -- Good point on leaks. It occurred to me that maybe they didn't seat the pitless right or something, but I suppose the system could be leaking anywhere along the tube or even at the new fitting on the pump. FYI, it's a modern bladder tank, so the valve is (as far as I can tell) a backflow check valve made by Flowmatic.

I read the "sticky" thread on check valves, and see the points behind that. None of the installers who quoted me batted an eye at the old tank-end check valve, one mentioned it would be part of the upgrade if I replaced the tank. So I assumed (but don't know) that Maryland is one of those states that requires the backflow prevention at the house.

Craig - The installer I used did the pump and the wire. He informally expressed the opinion that the poly tube was in OK shape, but didn't put that in writing. I guess I'll see what happens.

It sounds like replacing the top-side check valve would be a cheap fix for the pressure loss, but it would be hiding another problem down in the well. Probably to the detriment of the system.

It sounds like replacing the top-side check valve would be a cheap fix for the pressure loss, but it would be hiding another problem down in the well. Probably to the detriment of the system.

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I would get the installer back to make good on his warranty. As mentioned in the sticky, the topside checkvalve could cause waterhammer issues, the severity of which depends on what the static water level in the well is.

Got them coming back to look it. Meanwhile I talked to the installer on the phone - he immediately thought of the Pit-less and told me to go listen to the well. As he predicted, I can hear the faint "tinkle" of a slow leak dripping into the well when the tank is under pressure. He says they will come take a look at the O-ring and pressure check the bottom of the system.

I assume replacing the O-ring on the pitless is trivial? I also assume that they should have caught that before they left the first time at which point it would not have been additional labor...

On the other hand, he confirmed the house-end check valve IS required in Maryland. Is that something I need to replace completely, or can you simply refit the innards like replacing a washer? The old one is Flowmatic which I think is now Watts...given that I have to have one, is there a good brand?

You can replace the innards. But if you want a safe supply of water, you won't use a check at the house. With the "innards" removed, no one will be able to tell you don't haver a check valve. A check at the house can leave your underground pipe under a vacuum, which can draw in pesticides, herbicides, bacteria, and other stuff from the surface into your water supply.

I wanted to report back for the sake of anyone else perusing this thread.

The installer sent a someone out. He confirmed the leak, dripping at the pitless was fairly obviously with a bright enough light. So he pulled the coupling and replace the o-ring. Interesting aside, the pitless was old enough to use a leather O-ring; this guy said he'd never actually seen one in the field before. (Comments?) Anyway, he got a new O-ring from the supply house, slathered on some thread dope for good measure, and put it back in place. Seems to have solved the problem. (Never got around to fixing the checkvalve...so we'll just leave that be.)